rms orthodontic residents

1. Journal of Clinical and Diagnostic Research. 2015 Jan, Vol-9(1): ZE11-ZE14 1111
DOI: 10.7860/JCDR/2015/10529.5480
Review Article
Keywords: Diagnosis, Early displaced canines, Impacted canines, Radiographs
Introduction
Tooth impaction can be defined as the infraosseous position of the
tooth after the expected time of eruption, whereas the anomalous
infraosseous position of the canine before the expected time
of eruption can be defined as a displacement. Most of the time,
palatal displacement of the maxillary canine results in impaction
[1]. However, it is possible to prevent possible maxillary canine
impaction by recognizing the tooth displacements early. GPS i.e.
Global Positioning Satellite provides us location and the necessary
information anywhere on the earth; similarly this article will guide us
about different methods involved in localizing the canine that has
lost its path during eruption.
After the third molar, the most frequently impacted tooth is the
maxillary canine. Ericson and Kurol estimated the incidence at
1.7%. Impactions are twice as common in females (1.17%) as in
males (0.51%). Of all patients with maxillary impacted canines, it
is estimated that 8% have bilateral impactions. The incidence of
mandibular canine impaction is 0.35%.; the prevalence of impacted
maxillary canine ranges from a minimum of 0.92% to a maximum
of 4.3% [2].
According to Dewel [3,4], maxillary canines have the longest period
of development, as well as the longest and most tortuous course
to travel from the point of formation, lateral to the piriform fossa,
until they reach their final destination in full occlusion. Moss [5]
states that the canine remains high in the maxilla just above the
root of the lateral incisor until the crown is calcified. It then erupts
along the distal surface of lateral incisor resulting in closure of the
physiological diastema if present and correction of the so called ugly
duckling dentition [4,6].
Aetiology
In general, the causes for retarded eruption of teeth may be either
generalized or localized [4,7,8]. More recently, the absence of the
maxillary lateral incisor and variation in the root size of the tooth,
as well as variation in the timing of its root formation, have been
implicated as important etiologic factors associated with canine
impaction [4,9-11]. It seems that the presence of the lateral incisor
root with the right length, formed at the right time, is an important
variable needed to guide the mesially erupting canine in a more
favourable distal and incisal direction. Becker et al., [11] reported an
increase of 2.4 times in the incidence of palatally impacted canines
adjacent to the sites of missing lateral incisors as compared with
the general population. Two main theories have been proposed to
explain the occurrence of palatally displaced maxillary canines: the
“guidance theory” [10,12,13] and the “genetic theory” [14,15].
DentistrySection
Localization of
Impacted Canines
ABSTRACT
Impaction of maxillary canines is a frequently encountered clinical problem. The impaction of canine can be prevented in some situations
if the canine displacement is diagnosed in the early mixed dentition period and this would be extremely useful for the clinician. Hence,
it is very important to focus on the means of early diagnosis and interception of this clinical situation. In the present article, the different
modalities used to diagnose the impacted canine are reviewed with an insight into current 3-D modalities.
Surubhi Kumar1
, Praveen Mehrotra2
, Jitendra Bhagchandani3
, Ashish Singh4
,
Aarti Garg5
, Snehi Kumar6
, Ashish Sharma7
, Harsh Yadav8
Interception of canine impaction
The most critical point in the prevention of possible maxillary canine
impaction is the ability to recognize the tooth displacement early
and to predict the subsequent failure of eruption. The average age
when a maxillary canine should erupt is 13 y in boys and 12 y and
3 mnth in girls [4]. So, the ability to diagnose canine displacement
in the early mixed dentition (average age of 8 y) and to prevent
impaction of the canine would be extremely useful for the clinician.
The best time to begin assessing potential impaction is during the
early mixed dentition period, because the early diagnosis of one
dental anomaly may indicate an increased risk for later appearance
of others [2,15].
Localization of maxillary canine
Localisation of maxillary canine is based on both clinical and
radiographic examination.
Clinical evaluation: It has been suggested that the following
clinical signs might be indicative of canine impaction: (1) delayed
eruption of the permanent canine or prolonged retention of the
deciduous canine beyond 14 to 15 y of age, (2) absence of a normal
labial canine bulge, in other words, either inability to locate canine
position through intraoral palpation of the alveolar process or the
presence of an asymmetry in the canine bulge noted during alveolar
palpation, (3) presence of a palatal bulge, and (4) delayed eruption,
distal tipping, or migration of the lateral incisor [4].
According to Ericson and Kurol [16], the absence of the "canine
bulge" at earlier ages should not be considered as indicative of
canine impaction. In their evaluation of 505 schoolchildren between
10 and 12 y of age, they found that 29% of the children had non-
palpable canines at 10 y, but only 5% at 11 y, whereas at later
ages only 3% had non-palpable canines. Therefore, for an accurate
diagnosis the clinical examination should be supplemented with a
radiographic evaluation.
Radiographic Assessment: The proper localization of the
uneruptedmaxillarycanineplaysacrucialrole.Itcanhelptorecognize
the tooth displacement in mixed dentition to prevent subsequent
impaction. It also aids in determining the feasibility as well as the
proper access for the surgical approach and the proper direction for
the application of orthodontic force. Various radiographic exposures,
including panoramic views, periapical view, occlusal films, postero-
anterior views and lateral cephalogram can help in evaluating the
position of the canines. However, all these techniques help to
visualise the tooth in 2-dimensions. So, 3-dimensional radiographic
techniques including Computed Tomography (CT), Spiral CT, Cone
Beam Computed Tomography (CBCT) were introduced [17].

2. Surubhi Kumar et al., Tools for Localization of Impacted Canines: A Review www.jcdr.net
Journal of Clinical and Diagnostic Research. 2015 Jan, Vol-9(1): ZE11-ZE141212
[Table/Fig-4]: A) Panoramic radiograph tube effectively at +7 to occlusal plane.
Image of incisal tip of palatal canine is projected on film, on film, midway along lateral
incisors. B) Tube for maxillary OR is at +60. Image of incisal tip of palatal canine is
projected onto apex of lateral incisor i.e. the tooth farther away from tube has moved
in the same direction as the tube
[Table/Fig-5]: 3-D imaging of impacted maxillary canine
Following are the aids to localise the erupting canines:-
1. Panoramic Radiographs: Ericson and Kurol [18] in 1988
defined number of sectors to denote different types of impaction
[Table/Fig-1].
i. Sector 1: if the cusp tip of the canine is between the inter-
incisor median line and the long axis of the central incisor;
ii. Sector 2: if the peak of the cuspid of the canine is between the
major axes of the lateral and central;
iii. Sector 3: if the peak of the cuspid of the canine is between the
major axis of the lateral and the first premolar.
They used angle α to represent the angle formed between the inter-
incisor midline and long axis of canine and “d” as the perpendicular
distance of the peak of the cuspid of the impacted canine with
respect to the occlusal plane. Localisation via sector methods has
a more prognostic than diagnostic value. The risk of resorption
of the root of the lateral incisor increases by 50% if the cusp of
the canine belongs to sector 1 or 2 and if α angle is greater than
25°. The duration of treatment is longer if the canine is found in
sector 1, shorter if it belongs to sector 3, with respect to sector 2.
The necessity of treatment and the degree of treatment difficulty
increases as this angle increases.
Linduaer et al., [19] in the year 1992, gave another sector classifi­
cation and found out that 78% of canine that were destined to get
impacted had their cusp tips located in sector II, III, IV. Fernandez et
al., [20] in the year 1998 studied the eruption pattern of the canine and
found that during eruption; the upper canine increases its inclination
mesially, until a maximum angle is reached at approximately 9 y
of age. From this inflexion point onwards, the tooth progressively
straightens until it emerges above the gingival margin. When the
lateral incisor is not yet fully developed, panoramic radiographs
more commonly show overlapping of the canine and lateral incisor.
In contrast, when lateral incisor development is complete, such
overlapping is rare; moreover, the few cases in which it is observed
involve a greater mesial inclination of the canine. The overlapping of
the canine and lateral incisor in panoramic radiographs when the
incisor has completed its development may be a sign of eruptive
disorders of the canine, suggesting the adoption of preventive
measures to avoid impaction; for example, extraction of the primary
canine.
In the year 2003, Warford et al., [21] did a study for predicting the
maxillary canine impaction using sectors and angular measurement.
He localised the canine according to 4 sectors and measured the
angle between the bicondylar line and long axis of canine. He
concluded that the probability of canine impaction increases as the
angle reduces and the sector increases.
Sudhakar S and Patil K [22] concluded that a single panoramic
radiograph can serve as a reliable indicator for determining the
bucco-palatal position of the impacted canines when they lie in the
middle and coronal zones. When they lie in the apical zone it is
recommended to explore their presence with other conventional or
advanced imaging modalities.
Katsnelson A [23] et al., in 2010 concluded that panoramic
radiographs has a high sensitivity and specificity for determining
impacted maxillary canine position, with angulations greater than
65o associated with buccal impactions.
In 2012, Sajani and King [24] gave a reliable method for diagnosis of
early diagnosis of unilateral canine impactions. There was a clinically
discernible difference of 4 mm at the age of 8 y and beyond between
the mean distance of the tip of the impacted canine group and that
of the antimere group from the occlusal plane. Furthermore, there
was a statistically significant difference at the age of 9 y and beyond
between the 2 groups according to the position in different sectors
and according to the mean angle made with the midline. Diagnosis
of maxillary canine impaction is possible at 8 y of age by using
geometric measurements on panoramic radiographs.
2. Periapical Radiographs: They are the simplest radiographs
having minimum exposure. They provide us with information
regarding state of development of tooth, the presence of follicle,
resorption of deciduous tooth.
[Table/Fig-1]: Sector classification by Ericson and Kurol [Table/Fig-2]: Canine position on Lateral Cephalogram [Table/Fig-3]: Occlusal radiograph showing labially impacted
canine

3. www.jcdr.net Surubhi Kumar et al., Tools for Localization of Impacted Canines: A Review
Journal of Clinical and Diagnostic Research. 2015 Jan, Vol-9(1): ZE11-ZE14 1313
3. Postero-Anterior Views: Postero-anterior radiography is
fundamental for evaluating the medio-lateral position of the canines
with respect to a line connecting the inferior borders of the orbits.
However, this technique is more useful for carrying out a prognostic
evaluation rather than providing a diagnosis of position. This is
possible through the evaluation of the angle formed by the long axis
of the canine and the transorbital line. The prognosis and the degree
of treatment difficulty increase as the angle between the long axis of
the canine and the transorbital line decreases [25].
4. Lateral Cephalogram:- If the dental age of the patient is between
8 and 9 y, the upper canines can easily be located by means of
laterolateral teleradiography. This technique is useful in establishing
the height of the impacted tooth and the anteroposterior position
of the cuspid of the impacted canine with respect to the apices
of the incisors. This may be indicative to establishing whether the
impaction is in palatal or labial position. However, these data may
be misleading in the case of bilateral canine impactions due to
overlapping images of the two teeth. Evaluation of the impacted
canine is carried out by tracing its axis and intersecting it with
the perpendicular to Frankfurt’s plane [26]. Various angles can be
derived, whose significance from a prognostic point of view is as
follows [Table/Fig-2]:
Readings under 10° are considered to be within the norm;
1. between 15 and 25°, the possibility of the necessity of treatment
are increased;
2. between 25 and 45°, spontaneous growth is an exception and
the difficulties involved in treatment increase;
3. Over 45°, reservations as to the possibilities of treatment
success arise.
To assess whether the canine is impacted labial or palatal following
radiograph could be of a great aid:
1. Occlusal Radiographs: This may be carried out according to
various projections: the most frequently used is that of Simpson
(perpendicular beam to the film through the glabella). If, in the image
produced by this technique, the cusp of the canine is positioned in
front of the ideal line connecting the apices of the lateral incisors, the
position will be labial [Table/Fig-3] [27].
2. Clark’s Rule or Parallax Method or Tube Shift Method:
Parallax is the apparent displacement of an image relative to the
image of a reference object and is caused by an actual change
in the angulation of the x-ray beam. The change in angulation of
the beam is caused by a change in the x-ray tube position. The
reference object is normally the root of an adjacent tooth. Two
radiographs of the object are taken. First using the proper technique
and angulation as prescribed and the second, radiograph is taken
keeping all the parameters constant and equivalent of those of the
first radiograph, only changing the direction of the central ray either
with a different horizontal angulation or vertical angulation. A tube
shift may be carried out in either the horizontal or the vertical plane.
If the tooth shifts in the same direction as the tube then the tooth
is lingually placed and if it moves in the opposite direction then it is
buccally placed (SLOB- same lingual opposite buccal) [28].
Horizontal tube shift: Usually, periapical radiographs (PAS)
are used in illustrations of a horizontal tube shift but occlusal
radiographs (OR) are superior because they cover a larger area.
Therefore, the tube can be moved much more between the two
exposures resulting in the shift of the image of the impacted canine
being easier to determine as is discussed later. Frequently part or
the entire crown or the root of the impacted canine is not captured
on one or both periapical radiographs. The radiation dose from two
OR is comparable with that from two PAS [29].
Vertical tube shift: In 1986, Keur described a vertical tube shift
(VTS) using a rotational panoramic radiograph (PR) and an OR.
Because a PR is often taken as an initial radiograph, this combination
of radiographs only requires one additional exposure, the OR. The
PR tube is actually positioned behind the head at an angle of -7° to
the occlusal plane, and the film is in front of the head. However, to
aid interpretation of the VTS, the tube can be considered to be in
front of the head at an effective angle of +7° [Table/Fig-4a] because
the relationship of the image of the canine to the image of the lateral
incisor is unaltered. The OR is taken at an angle of +60° to 65° to
the occlusal plane [Table/Fig-4b], i.e., there is an effective difference
of 53° to 58° between the taking of the two films. The image of the
palatally impacted canine that is farther away from the x-ray tube
moves in the same direction as the tube [29].
3. Right Angle Technique: The right angle technique uses two
radiographs taken at right angles to each other. According to
Wraith, Ballard suggested the use of the combination of a lateral
cephalometric radiograph with a postero-anterior cephalometric
radiograph for localization of impacted maxillary canines. However,
the position of the impacted tooth is often difficult to interpret, and
an additional intraoral film is required to see the fine detail of the
impacted tooth and its surrounding structures. Another combination
of radiographs that may be used is a rotational PR and a vertex
(axial) or true OR, often supplemented with a periapical radiograph
[29].
4. 3-D Techiniques: Because of superimposition of structure on
the film it become difficult to distingusish the details which makes
the diagnosis and treatment planning difficult with conventional
radiographic methods. To be in a position to recommend best line
of treatment and to plan appropriate mechanotherapy strategy the
orthodontist requires following information-
1. The exact position of the crown and root apex of the impacted
tooth and orientation of the long axis.
2. The proximity of the impacted tooth to the roots of the adjacent
teeth.
3. The presence of pathology, such as supernumerary teeth,
apical granulomas, or cysts, and their relationship with the
impacted tooth.
4. The presence of adverse conditions affecting adjacent teeth,
including root resorption.
5. The anatomy and position of crown and root [17].
In recent years, CAT scans have become the technique of choice as
they supply more realistic information than traditional radiographic
methods. CT provides excellent tissue contrast [Table/Fig-5] and
eliminates blurring and overlapping of adjacent teeth. Despite its
advantages, until now, the use of CT for location of impacted teeth
and assessment of resorption has been restricted because of issues
related to cost, risk/benefit, access, and expertise in reading the
CT. Cone beam Computed Tomography was then introduced which
reduces the exposure to radiation [25].
5. Rapid Prototyping: CT studies provide a good visualization of
the spatial relationship between anatomical structures. However,
even when a 3D reconstruction is obtained, the analysis by the
orthodontist and the dental surgeon is still limited: 3D images are
seen as 2-dimensional (2D) on film and the computer screen. This
limitation can be overcome with the use of CT to make a model
by means of rapid prototyping. This technique comprises several
technologies that use data from computer-aided design files to
produce physical models and devices by a process of material
addition [30]. Dental modeling by means of rapid prototyping was
an efficient auxiliary method in diagnosis, orthodontic treatment
planning, and communication with this patient and the orofacial
surgeon.Rapidprototypingtechnologymadepossiblethefabrication
of an attachment for forced canine eruption. Rapid prototyping
dental modeling might become the diagnostic procedure of choice
in the evaluation of impacted maxillary canines [30].

4. Surubhi Kumar et al., Tools for Localization of Impacted Canines: A Review www.jcdr.net
Journal of Clinical and Diagnostic Research. 2015 Jan, Vol-9(1): ZE11-ZE141414
CONCLUSION
Recognition of tooth disturbances in early mixed dentition which are
genetically associated with canine impaction can aid the clinicians
in the early diagnosis of this clinical situation. If the displacement of
the canines is detected early, the clinicians should then focus on
the means of preventing a possible impaction. Clinically common
radiograph used to determine position of impacted canine is occlusal
radiograph or Clark’s method using two periapical radiographs,
the reason being the ease of availability and assessment. Other
supplemental radiographs like OPG, lateral cephalogram etc can
be used to decide the prognosis of impacted canine.
REFERENCES
[1] Litsas G, Acar A. A review of early displaced maxillary canines. Etiology, Diagnosis
and interceptive treatment. The Open Dentistry Journal. 2011;5:39-47.
[2] Ericson S, Kurol J. Radiographic assessment of canine eruption in children with
clinical signs of eruption disturbances. Eur J Orthod. 1986;8:133-40.
[3] Dewel BF. The upper cuspid: Its development and impaction. Angle Orthod.
1949; 19:79-90.
[4] Bishara SE. Impacted maxillary canines: a review. Am J Orthod Dentofacial
Orthop. 1992;101:159-71.
[5] Moss JP. The impacted canine. Dental Practioner. 1972;22:241-48.
[6] BroadbentBH.Ontogenicdevelopmentofocclusion.AngleOrthod.1941;11:224-
41.
[7] Bishara SE, Kommer DD, McNeil MH, et al. Management of impacted canines.
AM J Og'mot). 1976;80:173-90.
[8] Moyers RE. Handbook of orthodontics, Second Ed., Chicago: Year Book
Medical, 1963:83-88.
[9] Jacoby H. The etiology of maxillary canine impaction. Am J Orthod. 1982;84:125-
89.
[10] Miller BH. Influence of congenitally missing teeth on the eruption of upper canine.
Trans Br Soc Study Orthod. 1963164;50:17-24.
[11] Becker A, Smith P, Behar R. The incidence of anomalous lateral incisors in
relation to palatally displaced cuspids. Angle Orthod. 1981;51:24-29.
[12] Brin I, Becker A, Shalhav M. Position of the maxillary permanent canine in relation
to anomalous or missing lateral incisors: a population study. Eur J Orthod.
1986;8: 12-16.
[13] Mossey PA, Campell HM, Luffingham JK. The palatal canine and the adjacent lateral
incisor: a study of a west of Scotland population. Br J Orthod. 1994;21:169-74.
[14] Peck S, Peck L, Kataja M. Site-specificity of tooth maxillary agenesis in subjects
with canine malpositions. Angle Orthod. 1996;66:473-76.
[15] Peck S, Peck L, Kataja M. Concomitant occurrence of canine malposition and
tooth agenesis: evidence of orofacial genetic fields. Am J Orthod Dentofacial
Orthop. 2002; 122:657-60.
[16] Ericson S, Kurol J. Longitudinal study and analysis of clinical supervision of
maxillary canine eruption. Community Dent Oral Epidemiol. 1986;14:112-16.
[17] Chaushu S, Chaushu G, Becker A. The role of digital volume tomography in the
imaging of impacted teeth. WJO. 2004;5:120-32.
[18] Ericson S, Kurol J. Early treatment of palatally erupting maxillary canines by
extraction of the primary canines. Eur J Orthod. 1988;10:283-95.
[19] Lindauer SJ, Rubenstein LK, Hang WM, Andersen WC, Isaacson RJ. Canine
impaction identified early with panoramic rasdiographs. J Am Dent Assoc.
1992;123:91-97.
[20] Fernandez E, Bravo LA, Canteras M. Eruption of the permanent upper canine: a
radiologic study. Am J Orthod Dentofacial Orthop. 1998;113:414-20.
[21] Warford JH Jr, Grandhi RK, Tira DE. Prediction of maxillary canine impaction
using sectors and angular measurement. Am J Orthod Dentofacial Orthop.
2003;124(6):651-55.
[22] Sudhakar S, Patil K, Mahima VG. Localization of impacted permanent maxillary
canine using single panoramic radiograph. Indian J Dent Res. 2009;20(3):340-45.
[23] Katsnelson A, Flick WG. Use of panoramic x-ray to determine position of
impacted maxillary canines. J Oral Maxillofac Surg. 2010;68(5):996-1000.
[24] Sajani AK, King NM. Early prediction of maxillary canine impaction from panoramic
radiograph. J Orthod Dentofacial Orthop. 2012;142:45-51.
[25] Manverna R, Gracco A. Different diagnostic tools for the localisation of impacted
canines: clinical considerations. Progress in Orthodontics. 2007;8(1):28-44.
[26] Orton HS, Garvey MT, Pearson MH. Extrusion of the ectopic maxillary canine using a
lower removable appliance. Am J Orthod Dentofacial Orthop. 1995;107:349-59.
[27] Goatz PW, White SC. Radiologia odontoiatrica. Principi e interpretazione.
Padova: Piccin, 1986.
[28] Clark CF. A method of ascertaining the relative position of unerupted teeth by
means of film radiographs. Proc R Soc Med Odontol Sectn. 1910; 3 : 87-90.
[29] Jacobs SG. Radiographic localisation of unerupted maxillary anterior teeth using
the vertical tube shift technique. The history and the application of the method
with some case reports. Am J Orthod Dentofacial Orthop. 1999; 116:415-23.
[30] Faber J, Berto M, Quaresmaa M. Rapid prototyping as a tool for diagnosis and
treatment planning for maxillary canine impaction. Am J Orthod Dentofacial
Orthop. 2006;129:583-89.
PARTICULARS OF CONTRIBUTORS:
1. Private Practice,Orthodontist,Mumbai, Maharashtra, India.
2. Principal and Professor, Department of Dentofacial Orthodontics and Orthopaedics, Sardar Patel Post Graduate Institute of Dental and Medical Sciences,
Lucknow, Uttar Pradesh, India.
3. Reader, Department of Dentofacial Orthodontics and Orthopaedics, Sardar Patel Post Graduate Institute of Dental and Medical Sciences,
Lucknow, Uttar Pradesh, India.
4. Reader, Department of Dentofacial Orthodontics and Orthopaedics, Manav Rachna Dental College, Faridabad, Haryana, India.
5. Senior Lecturer, Department of Pedodontics, Jaipur Dental College, Jaipur, Rajasthan, India.
6. Senior Lecturer, Department of Periodontics, Rajasthan Dental College, Rajasthan, India.
7. Senior Lecturer, Department of Pedodontics, Rajasthan Dental College, Rajasthan, India.
8. Private Practice, Oral surgeon, Gurgaon, Haryana, India.
NAME, ADDRESS, E-MAIL ID OF THE CORRESPONDING AUTHOR:
Dr. Surubhi Kumar,
Flat No 202, Nav Swapna Society, Kalina, Santa Cruz East, Mumbai-40098, India.
Financial OR OTHER COMPETING INTERESTS: None.
Date of Submission: Jul 28, 2014
Date of Peer Review: Aug 27, 2014
Date of Acceptance: Sep 10, 2014
Date of Publishing: Jan 01, 2015